摘要
用XPS,XRD和IR技术研究了聚苯乙烯系吸附树脂负载的钯-铋双组分催化剂,考察了其催化氧化L-山梨糖的性能及动力学特征。结果表明,活性中心可能具有Pd^(2+)—O^(2-)—Bi^(3+)形式,在温和条件下可使其一步氧化为2-酮-L-古洛酮酸。反应对L-山梨糖为一级,对氧亦为一级,还对铋的助催化作用进行了讨论。
Supported bimetallic (Pd-Bi) catalysts were prepared by impregnating the nonpolar polyStyrene-divinyl benzene crosslinked adsorbing resin (D3520) with solution of PdCl2 and BiCl3. Pd-Bi/D3520 catalyst had good activity and selectivity for the oxidation of L-SorboSe, which could be oxidized in one step into 2-keto-L-gulonic acid. Pd and Bi of the catalyst were identified to be PdBi2 or Pd3Bi by XRD. XPS spectra showed that Pd2+ Pd°and Bi3+ existed on the catalyst surface. The interaction between support and metals was confirmed by IR Spectra. The active center of the Pd-Bi/D3520 catalyst in the form of Pd2+-O2--Bi3+ was suggested. Some kinetic parameters were measured and the oxidation mechanism was proposed.
